1. Field of the Invention
This invention relates to a new and useful process for recovering oil from oil shale containing kerogen, a solid organic, primarily hydrocarbon, material having a high molecular weight, i.e., greater than about 3,000 grams per mol, which comprises about 10 to about 30 percent by weight of oil shale. The percentage recovery, as oil, of the organic matter originally present in the oil shale is low by most methods known in the art. Even the best operations result in relative high conversion of kerogen to carbon and permanent gases, which are of low economic value compared to liquid fuels. Consequently, a need exists for a simple process for recovering oil from oil shale which results in high yields of liquid product. Accordingly, the present invention provides a higher yield of liquid product by a process for recovering oil from oil shale containing kerogen which comprises bringing a mixture of oil shale and solvent to a temperature in the range of about 385.degree. to about 440.degree. C. in a time period of less than about 10 minutes, maintaining said mixture at a temperature in the range of about 385.degree. to about 440.degree. C. and a pressure in the range of about 250 to about 2000 pounds per square inch gauge (about 1.72 MPa to about 13.8 MPa) for a period of about 20 minutes to about two hours and thereafter recovering the resulting oil.
2. Description of the Prior Art
Hampton in U.S. Pat. No. 1,778,515 states that it is old to subject a bituminiferous material, such as oil shale, to the digestive action of an oil bath to recover oil from oil shale. He states that increased yields of oil can be obtained by mixing oil shale of one-half inch mesh with a heavy oil, which may be preheated, heating the resulting mixture gradually to a temperature of 300.degree. to 400.degree. F. (144.degree. to 204.degree. C.), grinding the shale in the heated mixture until 60 percent or more thereof will pass 200 mesh, and then heating the ground mixture, most desirably suddenly, to a materially high temperature in the range of about 600.degree. to about 700.degree. F. (316.degree. C. to about 371.degree. C.). Hampton considers the possibility of feeding dry pulverized shale, without any accompanying oil, in controllable amounts into a hot digestion bath, but advises against the same because of technical difficulties.